-The Trump administration is preparing to ask Cuba to withdraw 60 percent of its diplomats from Washington, United States officials said Monday, in response to last week's USA move to cut its own embassy staff in Havana by a similar amount.

Secretary of State Rex Tillerson said, however, that Washington would maintain diplomatic relations even though the size of the USA mission in Havana would be reduced to a minimum.

US Secretary of State Rex Tillerson said the latest decision was made due to Cuba's "failure to take appropriate steps" to protect American personnel in Cuba who have been targeted in mysterious "attacks" that have damaged their health.

"This order will ensure equity in our respective diplomatic operations", he said.

After the departure of the Cuban diplomats, the number of personnel working in both embassies will be "roughly very close to each other", an official from the U.S. State Department told reporters.

The attacks, which United States officials initially suggested could have been carried out with some sort of covert acoustic device, have affected at least 22 USA embassy staff in Havana over the past few months.

Symptoms of these mysterious attacks have included hearing loss, dizziness and cognitive issues.

The moves deliver a significant blow to the rapprochement between the Washington and Havana that was launched by Barack Obama and Cuba's president Raúl Castro in 2015. The US will formally ask Cuba to pull the diplomats, but won't expel them forcefully unless Havana refuses, the officials said. The US has said the FBI is leading the investigation.

The move to push out the Cuban diplomats comes after the U.S. made a decision to pull back its own staff from the island nation after suspicious "health attacks" in Havana left some victims with hearing loss and speech problems.

The Cuban diplomats being expelled will not be deemed "persona non grata", officials said, a designation that would prevent them from ever returning to US soil.

Trump administration officials planned to brief lawmakers on their Cuba policy on Tuesday, another congressional aide said, speaking on condition of anonymity.

The decision came as the US told citizens not to visit Cuba and after it removed more than half of its staff from the Cuban capital of Havana.

The U.S. Department of State ordered 15 Cuban officials from the embassy in Washington, D.C., to leave the country.

United States transnational news agency Association Press gave impetus yesterday to Washington's assertion that USA diplomats in Havana have suffered mysterious sensory attacks by alleging that intelligence agents have been especially targeted. The departing Americans are expected to have all left Cuba by week's end, officials said.

The US expelled two Cuban diplomats in May, and Tillerson has raised the possibility of closing the American mission in Cuba altogether over the issue.

"The first disturbing reports of piercing, high-pitched noises and inexplicable ailments pointed to someone deliberately targeting the United States government's intelligence network on the communist-run island in what seemed like a bone-chilling escalation of the tit-for-tat spy games that Washington and Havana have waged over the last half century", the AP three declared.